Normally, upon printing an image sensed by a digital camera, the following processes are required. That is, an image stored in the digital camera is read by a personal computer (to be referred to as a PC hereinafter), and is printed by a connected printer using an application running on the PC.
That is, the flow of image data is DSC→PC→printer, and possession of the PC is indispensable. Also, the PC must be started to print an image stored in a DSC.
In consideration of such situation, some proposals in which a DSC and a printer are directly connected, and a print instruction is issued on a display normally equipped on the DSC (to be referred to as photo direct print hereinafter) have already been made.
Merits of use of the photo direct print system are easy print without starting a PC and low system building cost since a PC is not indispensable. Upon connecting a DSC to a printer, a display normally equipped on the DSC is used as means for giving various instructions and, especially, for confirming an image to be printed. Hence, a printer does not require any special display used to confirm an image, and the cost can be further reduced.
Most of recent DSCs comprise versatile communication means used to connect a PC. Typically, a DSC comprises a USB (Universal Serial Bus). Upon connection using this USB, a communication is established while defining the DSC as a slave and the PC as a host. When viewed from the PC side, the DSC can be handled like a simple external storage device.
Upon building a direct print system by directly connecting a DSC to a printer using such USB, it is desired to use the DSC not only as a simple storage device but also as a user interface device as the system unlike the DSC for the PC.
As described above, since most of DSCs have a USB interface, they can be physically connected to printers irrespective of whether or not they support the direct print function. Therefore, the printer apparatus side must determine (authenticate) whether or not the connected device is a digital camera which functions as a member of the direct print system. Images stored and held by a digital camera are normally managed as objects. Therefore, when a versatile communication means is used, if one of objects stores authentication information indicating that the camera is compatible to direct print, determination can be made on the printer side using even a normal protocol.
However, a memory (storage medium such as a CF card, smart media card, or the like) that can be attached to recent digital cameras can store and hold many images. Hence, the printer side must check object attributes one by one (if the contents of an object are transferred at that time, and that object is image data, the memory on the printer side overflows), and an authentication procedure takes much time.